Cooling unit



1'. w. CARRAWAY l COOLING UNIT Filed Oct. 20, 1937 4 Shana-Shut 2 mamas Q 3 is I 2 s Y I lll Carrawal y P 3, 0- r. CARRAWAY COOLING UNIT Filed Oct. 20, 1937 4 Shoots-Shout 4 lllllllallHHllll Thomas Garraway I 55' A further object is to provide a novel associae the coils 5. The headers 8-8 are connected by 55 Patented Sept. 3, 1940 I F I UNITED-STATES PATENT OFFICE COOLING UNIT Thoma'sW. Carraway, Dallas, Tex., assignor to Ideal-Aire, Inc., Dallas, Tex., a corporation of Texas Application October 20, 1937', Serial No. 170,117

8 Claims. (Cl. 257-70) This invention relates to cooling units, and tion of heat-transfer means and water-supplying more particularly to cooling units of the kind in means. I which a fluid to be cooled is passed through a Other objects will become apparent from a heat-transfer element such as a duct or the like, reading of the following description,the appendthe heat-transfer element being subjected to the ed claims, and the accompanying drawings, in 5 cooling effect of a stream of air passing in conwhich:

tact with the element, the air stream itselfand Figure 1 is a view in front elevation showing the element being cooled by evaporating moisture one embodiment of my invention;

in the air stream. Figure 2 is a vertical section taken on the Cooling units of this kind have been used line'3-3 of Figure 3; l0

heretofore principally because theycan be op- Figure 3 is a vertical'section takenv on the line erated somewhat more cheaply than cooling units 33 of Figures 1 and 2; I of the more generally used types in which the Figure 4 is a cross section taken on the line cooling is effected with the aid of compression 44 of Figure 2; I 1 I l5 expansion machinery or by the use of large quan- Figure 5 is a cross section taken on the line titles of water sprayed into the air beingcooled 55 of Figure 2; or conditioned. Generally stated, units of the Figure 6 is a view in vertical section coneclass to which my invention relates and which I sponding to Figure 2 but showing amodification; heretofore were known in the art comprised one Figure 7 is a section taken onthe line or more pipes; ducts, or the like through which of Figure 6; 20 air or other fluid to be cooled was passed, means I Figure 8 is a section taken on the line 8-8 of for spraying water on the ducts or pipes, and Figure 6; a means for moving air around the pipes wet by the Figure 9 is a longitudinal vertical sectional spray, the water thus sprayed on the pipes or view of a further modification;

ducts'evaporating and being carried away by the Figure 10 is a vertical cross section taken on 25 air stream as watervapor. The heat for evapthe line |0|0 of Figure 9; orating the water was drawn directly from the Figure 11 is a vertical cross section taken on pipes or ducts through which-the fluid to be the line II-ll of Figure 9; and I V coded was passed, Figure 12 is a diagrammatic view showing con- I have found that the efficiency of such units trol apparatus. I r -30 may be increased greatly by arranging the ducts The cooling units shown in the drawings are or pipes and the means for introducing the waillustrative of practical embodiments of the inter in such a way that, instead of spraying wavention, but it will ,be understood that the in- 1 ter almost directly upon the ducts or pipes, the vention may be embodied in other forms.

water is atomized and diiiused into the stream of Referring first to the form shown in Figures 35 air well removed from the pipes or ducts. I 1 to Sinclusive and 12, the cooling unit is shown have found that this eliminates, to a greater-eX- s, Comprising an upright Verti al casing A tent than heretofore has been considered possihaving inlet openings or louvers I at the bot ble, the carrying away of unevaporated particles tom end and discharge or outlet openings 2 at 40 of water, and results in maximum evaporation its upper end. A pair of blowers 3 is associated 40 whereby for a given quantity of water supplied to with the outlet openings, and is driven by means the unit a maximum cooling load canbe carried. such as a motor 4 for causing air to enter the An object of my invention, therefore, is to procasing through the louvers l to flow upwardly vide a cooling unit'of the class referred to in therethrough and to be discharged through the which the relative arrangementof the. ducts or openings 2 to any convenient point outside of 45 pipes and the water-supplying'means is such as the space to which cooled air or other fluid is to promote maximum evaporation of the water to be delivered. supplied to' the air stream, and hence'to produce Mounted within the casing is a heat-transfer I I amaximum cooling effect; unit B which in the form-shown includes two' Another object is to provide a unit of the kind horizontal coils 5-5 having inlets 6-45 and ex- 50 referred to in which the arrangement is such as tending back and forth through fins or radiator to produce a soitQevenflow of air around the plates 1. The outlet ends of the coils 55 are pipes or ducts, such flow having been found to be connected respectively as at B -6 to headers most conducive tomaximum evaporation. 8-8 disposed under and closely contiguous to cross headers '8 Connected to the several cross headers 8 are two sets of ducts 9 and 9' symmetrically disposed on opposite sides of a plane central and longitudinal or vertical with respect to the casing, such plane being perpendicular to the paper in Figure 2 and along the section line 3-3. The ducts 9 are all relatively close to each other, as are the ducts 9, so as to provide relatively small spaces therebetween. Thebottomends of the ducts are connected to'cross headers III which in turn communicate with headers Ill communicating with a discharge pipe or conduit I I.

Near their central points the ducts 9 are curved inwardly as at I2 towards theducts 9', and, conversely, the ducts 9' are curved inwardly at their central portions as at I2 toward the ducts 9.

On opposite sides of their central portions, i. e.,

' both above and below their central portions, the

ducts are curved outwardly as at I3, so that the ducts 9 become disposed relatively far from the ducts 9, and the ducts 9' become disposed relatively far from the ducts 9. As a result of this curvature of the ducts, there are provided two relatively large uninterrupted spaces I5-I5 between the central portions of the ducts and the walls of the casing, and two relatively large unin- 'terrupted spaces I6--I6 between the ducts 9 and the ducts 9'. The provision of these spaces around and between the ducts is of particular importance, as will now be explained.

Positioned within and arranged to discharge directly into the spaces I5-I5 are atomizers II'--I'I, and, similarly, atomizers I8I8 are positioned within and arranged to discharge directly into the spaces IB-I 6. Water is conveyed to the atomizers by means of a pipe I9 leading to the atomizers I8-I8 and having a branch 20 leading to the atomizers I'I-II. The water may be supplied by any suitable source of water under pressure, but preferably, and in accordance with a further feature of the invention, the water is supplied from a sump or reservoir 2| in the bottom of the casing, from which water may be drawn by a pump 22 operated by a motor 23, the inlet side 24 of the pump communicating with the reservoir and. the discharge side being connected directly to the pipe I9.

In operation, the blowers 3 are run continuously in order to maintain a steady flow of air upwardly through the casing A around and in contact with the ducts 9 and 9. The-fluid to be cooled is delivered to the inlet ends 6 of the coils 5, and, after passing through the coils, it flows downwardly. into the headers 8 and 8*, thence downwardly through the ducts 9 and 9,

I and thence outwardly through the bottom headers and the discharge connection I I. Water is delivered under pressure, to the atomizers I1 and I8, the latter spraying flnely atomized water into the spaces I5 and I6 respectively. Because of the relatively large spaces I5 and IS in which the atomizers are located and into which they discharge, the water will be thoroughly atomized, spread out, and diflused in the stream of air flowing upwardly through the casing. The atomization thereby effected is much more thorough and efficient than would be the case if the water were sprayed more directly upon the ducts; I have found that, when the ducts are wet with a rather thick layer of unatomized water because of the atomizers being located too close to the ducts, there is a tendency for the air stream to pick upsmall drops or globules of.

unatomized water and to carry it entrained in ducts.

the air stream out through the casing. Water 7 which is removed from the casingwithout first being converted into water vapor results in a substantial increase in the cost of operation, since it is chiefly the evaporation of the water which extracts heat fromthe ducts 9 arid'con: sequently from. the fluid flowing through the Furthermore, a relatively thick coatingor' layer of water on the ducts has a substantial insulating effect, interfering with and retarding In accordance with my in-,

vention a very thin filmof water ,or moisture is I 'maintained onthe duct surfaces; the film being so thin as to'fevaporate readily an'd inoreover .is not thick enough .to have any appreciable insulating effect. It is apparent that, although "my."

the heat transfer.

novel and improved arrangement of the ductsv and atomizers provides for particularly eflicientfl atomization and heat transfer, this desirablev result is accomplished without spreading the entire heat transfer unit, and therefore without increasing the size of and rendering bulky the unit considered as a whole. It should be noted that air entering the bottom of the casing is directed downwardly at first by the louvers I, so that, by the time the airreaches the ducts, there will be no substantial localized concentrations of air velocity, and instead there is a soft substantially uniform flow of air throughout the- 5 entire cross section of the casing. Such an even flow of air has been found to cooperate most efficiently with the novel arrangement of the atomizers within the spaces. the louvers I, flows substantially straightway enlarged atomization- Asis apparent, the. air, after entering through the casing in a direction opposite the general direction of flow of the fluid to be cooled through the ducts 9 and 9'. The" counter flow of the air and the fluid to be cooled produces the maximum cooling effect with the use of a, give quantity of water and cooling air.

Units of the kind described are adapted for refrigerating medium is conducted through the eral nature are well adapted for'cooling'of other f cooling the refrigerating medium usedin a compression-expansion apparatus, in which case the fluids, such as water or -oil as well as the direct cooling, of air, in which case the. air to be cooled is conducted through the ducts I and l and delivered to the roomor other space'to be conditioned or cooled. when used for cooling air,'it may be desirable to increase somewhatthe cross-sectional size,of the ducts to permit the free and easy flow of relatively large volumes of air.

Control. means are provided for maintaining a proper quantity of water-inthe sump'or reservoir 2 I, and for giving a signalin case thewaterin the sump or reservoir should drop below a predetermined level. -A's shown in Figures 2 and 12 the sump 2| is fed 'by& main water supply;

pipe 25, flowfrom which is controlled by a valve 26 which is in turn controlled'bya float -21; The arrangement is such that,'when the water inthe sump falls below a predetermined level, 'the determined level the float will rise to close the valve 28. v v

Control means is provided for the water suptrol means may comprise a float operated switch v float will descend, opening the valve 26, whereas,'when the water reaches or is above a prei j switch 32. -'Ilhe-c enjtral pole 32 of theswitch interposed therein -a temperature responsive .7 switch 33 ,'th'e purpose of which will be described means adapted to stop thepump motor and to actuate the signal when the water in the reservoir vdrops below a predetermined level whichv should be somewhat below the level at which the valve 26 opens to introduce morewater into the reservoir. One form of such control means is shown diagrammatically in 'Fig -I2as being in circuit with electrical supply conductors'28 and 29 controlled by'a master switch 28 -A conductor-30 leads from the conductor 28 to ,a-branch 32 iscohnected to'a conductor 29 which-has later. .The conductor 29 leads from the-switch 33 through the master switch 28 to the supply conductor 29. The parts thus far described con 'stit-ute the circuit for operating the signal 3!.

V The circuit for controlling the operationof the pump in dependence upon-the level of water in the reservoir. includes the supply conductor 28 leading through the s'witcha28 to the con- .ductor 30, which has abranch 34 connected to one side of the pump motor 23. 'I'heother side of the pump motor is connectedto a conductor 35' which leads to an end terminal 3201 the switch 32. conductor 23 which-leads from the central terminal 32 of the switch 32 through the temperatur responsive switch 33 and the master switch r28e touthe mainsupply conductor 29.

The operation of" the control means as' influenced by the level ofthe water in the reservoir will be described, first assuming that theswi'tch 33 is 'closed. Assuming also that the pump is running to deliver water from the reservoir to the atomizers,-the switch 32 will be in the position shown in Figure 12. In this position, the

motor circuit will be-closed-from the conductors 28, 30, 34, 35, the switch terminals32 and'32 the conductor 29 and the switch 33 to'the con ductor 29 The-water level will descend until the float has dropped "sufliciently to open the valve 28 to admit more water to the tank. If the supply-of water throughthe pipe 25 is unfailing the level of water in the tankwill rise until thefloat cuts oil? the valve 28. If, however, the water H supply: should fail, the float will continue to descend below the level at which it opens the valve 25" until the switch 32 has. been'tipped clockwise-as viewed in Figure 12, causing the i mercury to bridge acrossthe terminals 32 and "32 This will complete a circuit through the conductors 23,30 39, the signal 3|, the conductor 30, the switch 32, the conductor 2.9" and the switehf33 solas 'to actuate the signal indicating that the water supply has failed and giv ing the necessary,warning. I At the same time, tipping of the switch'32 will break the circuit between the switchterminals 32 and 32, thereby opening the motor circuit and stopping the pump. It is, of particular importance that'the switch 32 be so= mountedand positioned that bridging 'of the cinitacts 32 and 32 will be main-. tainedfor some time after the. float has de. scended to a position to .open the valve 26-. In normal'operation the float will descend to a po sition opening the. .valve 29 frequently so as to replenish the water supply, but the signal 3| should not be actuated and the pump should Included .also in this circuit is thenot be stopped unless the float descends to a considerably lower position.

' I provide. means for cutting 01f the supply of contrary, when the air drawn from theoutside is at a low temperature, say below freezing, it may not be necessary to employ atomized water for effecting the necessary heat abstraction, the low temperature of the outside air itself suilicing to effect the required heat transfer. For this reason I prefer to provide means responsive to the temperature of the outside air or the air entering the casing, for discontinuing the supply of water to the atomizers when the temperature of the outside air reaches a predetermined low point. In the form shown in Figure 1.2 the switch 33 is interposed in the pump and signal circuits and is adapted to be maintained closed during summer operation by means of any suitable devicc responsive to the temperature of theoutside air, such, for example, as a sylphon bellows 31 com municating by means of a tube'33 with a container 39 for a thermo-responsive fluid medium; When the outside air is above a predetermined temperature the fluid within the container 39 will expand causing the bellows 31 to close the switch 33 and thereby causing the motor 23 and the pump 22 to operate so as to supply water to the atomizers. When, however, the temperature of the outside air falls below a predetermined value the fluid within the container will contract, causingv the switch 33 to be opened so as to stop the pumpand-motor and to discontinue supply of water to the atomizers. Furthermore, opening of the switch 33 will render the signal circuit inoperative. By virtue of this arrangement a substantial economy in the use of water is effected. Since I the entire operating expense consists of the cost of the water and "the cost of power for operating the blower and pump motors, dispensing whenpossible with one of these items of expense, namely the cost of the water, results in a material gain in operating economy. Moreover, ,it eliminates the danger of freezing which otherwise might occur', if water were supplied into the casing when the air entering the casing is below the freezing temperature. It is apparent that control means such as those described above may also be used for controlling thesupply of water when furnished directly from a city supply line without the use of a pump.

-I pr0vide means for giving a warning in the. event the pressure in the heat exchange ducts should rise due, for example, to failure of the atomizers to deliver sufficient water vapor to erate'the warning signal even though the water In' theform' shown, this signalling means includes a' 'signal device 100, such as a bell or light, and a may be at the desired. level in the sump.

switch I62 connected in series across the conductors 28 and 30. but it is adapted to be closed in response to risin; pressure in the ducts 9--9' and header 8 by means of a bellows I63 which communicates with the ducts and header 8 by means of a pipe I04. The modification shown in Figures 6, '7 and 8 is constructed and arranged to operate in much the same basic manner as the form shown in Figures 1 to 5. In the modification, the unit includes a vertically extending casing C provided with an inlet opening constituted by louvers 4|, and an outlet opening 42 arranged to receive and discharge air delivered by a blower 43xdriven bya motor (not shown). The heat transfer unit D disposed within the casing'differs specifically from the unit B shown in Figures 2 and 3. The unit D includes upper spacedheaders 44 connected by cross headers Sets of ducts 46 and 46' respectively are connectedat their upper ends to the cross headers, and at their bottom ends are connected to cross headers .61 communicating at their opposite ends with headers 48. The ducts 46 are. relatively close to each other so as to provide relatively small spaces therebetween, and the ducts 46 are relatively close to each other, providing relatively small spaces therebetween.

As shown in Figure 6, the upper ends'of the ducts 46 are disposed at the left of the casing, and the ducts extend on an incline downwardly and to the right, being connected to the cross headers 41 adjacent the right hand side of the casing. Conversely, the ducts 46' are connected to the upper cross headers adjacent the right hand side of the casing, and extend downwardly on an incline toward the left, and are connected to cross headers 41 adjacentthe left hand side of the casing,'the arrangement being such that the ducts 46 cross the ducts 46 as at 46 at about the middle of the casing, Preferably, the ducts are all curvedas shown, inorder to provide enlarged spaces 69-49 between the ducts 46 and the ducts and enlarged spaces 50 between the ducts and the sides of the casing. A fan or blower 5| is arranged to draw fluid to be cooled in through an inlet duct 52, and to deliver it to Q .the headers 44. Preferably a.filter 53 is disposed ll 49 and 50.

in the path of the incoming air. The enlarged spaces serve a purpose analogous to that of the spaces l5 and IS in Figure 2, that is to say, they provide spaces for complete atomization of water delivered by atomizers 54 and55 located within and arranged to discharge directly intotlie spacer: The atomizers are supplied with water under pressure from a, pipe'liG having a; branchgSfI.

{,In 0 'eration, the blower 63 is run continuously so" as 0 provide a steady uniform flow of lair up through the casing around and in contact with the ducts 45 and'46. The blower .5! draws in the alror other fluid to be cooled or conditioned, and forces it through the ducts, from whence it is discharged through the cross headers 41 and 48, being then delivered to the space to be cooled. As in the case of the ru shown in Figures 1' to 5, the modification shown in Figures 6 to 8 may be, used for cooling either air to be delivered to a room or therefrigerating medium of a compression-expansiomrefrigerating apparatus. If used for the latter purpose'ithe blower 5| would be replaced by the usual compressor, and the ducts would be connected in circuit with the compressor and expander. It is apparent that the modification shown in Figures Normally, the switch is open 6 to 8 may be operated in connection with an automatic control of the kind shown in Figure 12 and previously described.

The modification shown in Figures 9'to 11, inclusive, is especially adapted for conditioning of air to be delivered tea room or other space to be cooled. This unit includes a horizontal casing E having an inlet end 58 and an outlet end 59, a blow er 60 operated by a motor 6| being arranged at the outlet end for drawing air through the easing. Rectangular headers '62 and 63 are disposed respectively near the inlet and outlet ends of the casing, and interposed between the headers are two sets of ducts and 64'. These ducts are large in cross section so as to permit the easy flow of air with as little friction as possible. Flow of air through the ducts is induced by means of a blower 65 driven by a motor 66 and communieating with the header througha large intake 61 interposed in which is a filter 68. The ducts 64 and '64 are shown as being of rectangular cross section, but in accordance with the invention they'may be of other shapes. It is of importance. however, that they be curved from end so as to provide relatively large atomi zinrz spaces 16 and 1| in which are positioned'atomizers 12 and 13. 'In this form also the relatively large spaces 10 and 1| provide for the substantially complete atomization of water delivered by the atomizers, and consequently result in the maximum cooling effcct of the water supplied to the atomizers. The water may be supplied-tothe atomizers from any suitable source by mcans'of'a pipe 14. Drain cocks 15 are provided for draining off condensate which forms within the ducts 64 and 64 when the ducts are at a temperature lower than the dew'point of air passing through the ducts. The casing may be provided with a drain connection 15 for removing such slight 62. Air enters the ductsto end as shown in Figure 9 amount of water as may collect unatoinized at the bottom of the casing.

A filter 16 is provided at the inlet end 58. Insofar as I am aware, filters have been used heretofore only in the stream of air which is to be delivered to the conditioned or cooled area. 'In accordance with this feature of my invention, I position the filter 16 in the path of the air which flows around th eclutts and. is later exhausted to the outside in=tead of being clelivercd to the conditioned space. Not only docs the filter 16 act to prevent the ducts from becoming coated as it enters the casing and causing it to flow in,a

. very uniform stream throughout the length of the casing. As previously stated, such even and uniform flow without any localized air velocities is highly conducive to atomization of a maximum part of the-water delivered by the atomizers; I

It will be observed that in all-of thedisclosed forms of the invention the atomization spaces not only are sufficiently large to give the water sprays an opportunity to fan out" and thus become thoroughly atomized, but moreover they are not interrupted by baffles. fins, or the like, so that the steady even flow of air through the spaces is not interfered with. 1

The cooling units disclosed herein embody my inventionrnfpractical and the at present preferred forms, butf it, will be understood that changes may be madenvithoutdeparting from the invention as defined in the claims.

aaiaesa.

. ing;.two sets of ducts symmetrically disposed therein respectively on opposite sides of a plane longitudinal and central with respect to the cas ing; means for moving air through said casing,

the central portions of the ducts of each set being curved inwardly towards ducts of the other set and towards said plane providing resultant enlarged air spaces or pockets between the castively large spaces and effective to bathe all said duct portions in a very thin film of water; and means for supplying water to said atomizing means. i

2. In a cooling unit, the combination of a casing having aninlet end and an outlet end; a plurality of ducts therein for conducting fluid to be cooled; means for moving air substantially straightway through said casing from the inlet end to the outlet end, said ducts having portions lying relatively close together with small spaces therebetween and being shaped intermediate their ends to form other portions relatively far apart and providing resultant relatively large spaces therebetween and providing at least'one such relatively .large space at a location other than at or adjacent the inlet end of the casing; and atomizing means opening directly into said relatively large spaces and arranged to spray atomized liquid into said spaces and effective to bathe all said duct portions in a very thin film of water.

3. In a cooling unit, the combination of a casing; two sets of ducts symmetrically disposed therein respectively on opposite sides of a plane longitudinal and central with respect to the casing; means for moving air through said casing, the central portions of the ducts of each set being curved inwardly towards ducts of the other set and towards said plane providing resultant enlarged air spaces or pockets between the casing and said inwardly curved duct portions; and atomizing means opening into said spaces and arranged to spray atomized liquid into said spaces.

4. In a cooling unit, the combination of 9. casing; two sets of ducts symmetrically disposed therein respectively on opposite sides of a plane longitudinal and central with respect to the easing; means for moving air through said casing,

the central portions or the ducts of each set being curved inwardly towards'ducts of the other set and towards said plane providing resultant enlarged air spaces or pockets between the casing and said inwardly curved duct portions, the portions of the ducts intervening between said inwardly curved central portions and the ends of the ducts being curved outwardly away from said plane and thereby providing resultant air spaces or pockets between the respective sets of ducts at opposite ends thereof; and atomizing means opening into said spaces and arranged to spray atomized liquid into said spaces.

5. In a cooling unit, the combination or a casing and said inwardly curved duct portions, the

, portions of the ducts intervening between said inwardly curved central portions and the ends of the ducts being curved outwardly away from said plane and curved backinwardly to provide additional resultant air spaces or pockets between the respective sets 01 ducts; and atomizing'means opening into said spaces and arranged to spray atomized liquid into said spaces.

6. In a cooling unit, the combination of a casing; two sets or ducts disposed symmetrically,

therein, the ducts or one set extending diagonally from one side of the casing across the casing and to the opposite side thereof and the ducts oi! the other set extending diagonally from said other side 0! the casing acrossthe casing and tothe first named side of the casing, the ducts of the two sets crossing each other and the said arrangement of ducts and the casing providing a plurality of relatively openand uninterrupted spaces; means for moving air through said casing; and

, atomizing means opening into said spaces.

means opening directly into said relatively large space and efiective to bathe said duct portions with a very thin film of water; and means for supplying water to said atomizing means.

8. In a cooling .unit, the combination 01' a casing; a plurality of ducts therein for conducting fluid to be cooled; means for moving air through said casing in contact with said ducts, said ducts respectively having spaced portions lying relatively close to a wall ofthe casing and providing relatively small spaces respectively between said duct portions and said wall, and intervening connecting portions extended away from said wall and then back toward said wall, said intervening duct portions collectively and the portion or said wallopposite said intervening portions being separated by a relatively large space; atomizing means opening directly into said relatively large space and eflective to bathe said duct portions with a very thin film of water; andmeans ion supplying water to said atomizing means.- v,

THOMAS W. CARRAWAY. 

